The objective of this program is to develop suitable methods of cell cycle analysis with which the growth kinetics of cancer and normal cells from man and experimental animals can be understood in the context of cancer therapy with drugs and radiation. Flow cytometric studies of the response of Lewis lung tumor cells to single doses of vincristine, ara-C or hydroxyurea will continue and studies of the response to multiple doses will begin. Both cell cycle traverse and cell survival will be studied. Our computer program for the automatic analysis of flow systems data cell populations responding to a single perturbation will be improved to allow analysis of the response to multiple drug treatment. Studies of the kinetic properties of heterogeneous cell populations will be made utilizing multiple staining; for example, one stain will differentiate between normal and tumor cells and the other will be specific for DNA content. We will continue to analyze FLM and RCSi and data as a service, and to compile the results periodically in search of kinetic differences between malignant and normal cells. A study of the accuracy of the FLM and RCSi methods will be initiated.